Field of the Invention
The present invention relates to an internal rotor-type fluid machine which includes a rotor configured to be rotated while being supported by a rotary shaft, and which may be preferably applied, for example, to a gear pump device such as a trochoid pump for pumping a liquid by gear engagement between an inner rotor and an outer rotor.
Description of Related Art
For example, JP-A-H11-132160 discloses an internal rotor-type fluid machine. The internal rotor-type fluid machine has a structure in which a rotary shaft is fitted into a center hole of a rotor, and a support portion is provided at a center position of the rotor in an axial direction on an entire inner peripheral surface, which configures the center hole of the rotor, to protrude therefrom. In a case where the center hole of the rotor has a simple cylindrical shape without providing the support portion, when a force is applied to the rotor inwardly in a radial direction, the inner peripheral surface of the rotor comes into line contact with the rotary shaft. Accordingly, if the rotary shaft is tilted, the rotor is also tilted. In view of this problem, the support portion is provided on the inner peripheral surface of the rotor to protrude therefrom at the center position in the axial direction, so that the support portion is brought into point contact with the rotary shaft. According to this configuration, even when the rotary shaft is tilted, the rotor is not tilted. Since the rotor is configured to be not tilted as described above, gap generation between the rotor and an end surface of a case can be suppressed, thereby ensuring sealing performance between the rotor and the end surface of the case.